This invention relates to the field of light measuring devices, and in particular, to radiometers and other light energy sensors and non-imaging imaging light collection systems.
Many applications of light require an accurate determination of the absolute or relative amount of light energy produced and or delivered. With the growing use of light in many industrial processes, there has been an increased demand for compact, robust, radiometrically accurate instruments for light energy quantification.
In typical light measuring applications, a radiometer is used to determine the quantity of light energy output from the light emitting device. However, because the emitted light energy may not be uniform (typically as a result of variations in input beam radiance and intensity profiles), for improved accuracy, non-imaging interfaces such as planar diffusers or integrating spheres are interposed between the emitter and the radiometer. Planar diffusers sacrifice transmission efficiency for uniformity and are limited in terms of the homogeneity they can provide for non-uniform sources. Prior art integrating spheres typically have a housing (which may be made out of aluminum or other rigid material), the inner spherical cavity of which is coated with a reflective substance. In their paper, xe2x80x9cReflection properties of pressed polytetrafluoroethylene powderxe2x80x9d, Weidner and Hsia discuss such a process of pressing polytetrafluoroethylene (PTFE) powder, which is an excellent diffuse reflector of light energy, to coat the inner surface of an integrating sphere.
U.S. Pat. No. 4,912,720 issued to Springsteen describes the process of molding pressed powder PTFE into a block, which is sintered through a heating process and machined into a desirable shape. U.S. Pat. No. 5,537,203 issued to Carr, utilizes this process to make integrating spheres.
Sufficiently accurate prior art integrating spheres tend to be relatively large and bulky, and/or the prior art techniques for manufacturing them are typically time consuming and expensive. There is accordingly a need for a compact integrating cavity. There is also accordingly a need for an integrating cavity which is relatively easy and inexpensive to manufacture.
The present invention is directed towards a light integrating interface.
The subject light integrating interface comprises a light energy input port having a longitudinal axis, a light energy output port having a longitudinal axis, and an integrating cavity operatively coupled to the input port and to the output port. The integrating cavity is non-spherical and comprises a reflective inner surface. The input port longitudinal axis lies in a plane which is substantially parallel to and displaced from a plane in which the output port longitudinal axis lies. The subject invention is also directed towards a light sensor comprising such a light integrating interface.
The subject invention is further directed towards a light integrating interface comprising a housing consisting substantially of pressed polytetrafluoroethylene powder, an integrating cavity positioned within the housing, a light energy input port having a longitudinal axis, and a light energy output port having a longitudinal axis. The input port and the output port are operatively coupled to the integrating cavity. Additionally, the subject invention is directed towards a light sensor comprising such a light integrating interface.